The joint service "US British Seapost" existed from May 10, 1905 until August 25, 1914, when it ended due to the outbreak of World War I
and the British participation. However, it was continued by the USA alone until 1917, when they entered the war.
It consisted of seven White Star Line ships and four United States Line ships.
British and American postal employees worked in the on-board post office. The American ones on the voyages to Europe, the British ones on the voyages to the USA.
The ships of the US Line used stamps with the numbers 1 to 4 in the killer. I show here only covers with the postmarks of the American ships.
- Nr. 1 - S.S. New York
- Nr. 2 - S.S. Paris (umbenannt in Philadelphia 1902)
- Nr. 3 - S.S. St. Louis
- Nr. 4 - S.S. St. Paul
Accoding to Cockrill Booklet No 54
Source reference:
Cockrill, Booklett No 54 und No 55
Hosking, Seaposts of the USA
Overstamped commercial postcard with postmark type A4 to Cockrill with number 1 in the killer. Postmarked on XX. May 1907 aboard the American Line steamer "New York". Addressed to East Oakland, Calif.
Overstamped commercial postcard with type A4 postmark to Cockrill with the number 2 in the killer. Postmarked 03 Jun 1914 aboard the American Line steamer "Philadelphia". Addressed to Bridgen, N.J., forwarded to Brooklyn, N.Y.
Overstamped commercial postcard with type A4 postmark to Cockrill with number 3 in the killer. Postmarked 23. March 1912? on board the steamer "St. Louis" of the American Line. Addressed to San Francisco, Calif.
Overstamped commercial postcard with type A4 postmark to Cockrill with the number 4 in the killer. Postmarked Aug. 10, 1907 aboard the American Line steamer "St. Paul." Addressed to Edgewater, N.J.
As required franked commercial postcard with type A4 postmark to Cockrill with the number 4 in the killer. Postmarked Dec. 22, 1910 aboard the American Line steamer "St. Paul." Addressed to West Lym, Mass.
Overstamped commercial postcard with type A4 postmark to Cockrill with the number 4 in the killer. Postmarked April 24, 1914 aboard the American Line steamer "St. Paul". Addressed to New York, N.Y., forwarded to Milford, Conn.
As-needed postcard with postmark type A4 to Cockrill with the number 4 in the killer. Postmarked 02/20/.XXXX at Callao, Peru, (reverse side) accidentally caught aboard American Line steamer "St. Paul" and postmarked "missent" there. Addressed to Weymouth, Nova Scotia, Canada.
